FIG. 1 is a cross-sectional view of a prior art assembled valve apparatus 1 having a sealing surface 3a of annular valve seat 2a sealed to a valve ball 4, and a sealing surface 3b of an annular valve seat 2b sealed to valve ball 4. The following discussion, while directed to an annular valve seat 2a, applies equally to an annular valve seat 2b. In order to facilitate a seal between sealing surface 3a and valve ball 4, sealing surface 3a is machined on annular valve seat 2a prior to the assembly of valve apparatus 1. As a result, when valve apparatus 1 is assembled, sealing surface 3a will contact and seal with valve ball 4. FIGS. 2A and 2B are illustrative of a design of sealing surface 3a.
Referring back to FIG. 1, when valve apparatus 1 is assembled, pressure applied from valve ball 4 to sealing surface 3a energizes the seal between sealing surface 3a and valve ball 4. In order to maintain an energetic seal between sealing surface 3a and valve ball 4 over the life of valve apparatus 1, it is essential that sealing surface 3a applies an opposing pressure to valve ball 4. To provide sealing surface 3a with such an opposing pressure, valve apparatus 1 further includes an o-ring energizer 5a placed in an annular valve body pocket 7 of valve body 6. O-ring energizers 5a and 5b, and annular valve body pockets 7a and 7b are shown.
The following discussion, while directed to o-ring energizer 5a and annular valve body pocket 7a, applies equally to o-ring energizer 5b and annular valve body pocket 7b.
As valve apparatus 1 is assembled, o-ring energizer 5a is flattened within annular valve body pocket 7a. O-ring energizer 5a is made of resilient material, and as a result, o-ring energizer 5a wants to return to its original shape. The energy used by o-ring energizer 5a in its attempt to return to its original shape is provided to annular valve seat 2a, which in turn applies this energy as an opposing pressure along sealing surface 3a to valve ball 4. Thus, the seal between sealing surface 3a and valve ball 4 is further energized and can be maintained over the life of valve apparatus 1. FIGS. 3 and 4 are illustrative of the pre-assembled position and the assembled position of valve seat 2a, valve ball 4 and o-ring energizer 5a.
FIG. 1 is a generic drawing of a prior art valve apparatus, while U.S. Pat. Nos. 3,794,291, 4,099,705, 4,262,691, 4,718,444, 4,953,587, 5,170,989, and 5,263,685, are specific examples of valve apparatuses including annular valve seats having a pre-designed sealing surfaces and o-ring energizers. In some cases, springs are utilized. While these prior art annular valve seats are effective, such prior art annular valve seats involve multiple components and secondary operations in order to shape a sealing surface on the annular valve seat. The apparatus is highly specialized and directed to specific needs. In addition, the prior art annular valve seats are not designed to be self-energizing. Thus, o-ring energizers and/or springs must be utilized, and this also adds to the cost of the valve apparatus. Therefore, there is a need to provide an economical method for creating and energizing a seal between an annular valve seat and a valve ball.